Off-peak water heating system



Dec. 16, v1941.

OFF-PEAK WATER HEATING SYSTEM filed Nov. 12, 1940 5 Sheets-Sheet lINVENTOR @LAR/ STER/1R40 BY Wg@ ATTORNEY De- 16, 1941- c. M. OSTERHELD l2,256,248

OFF-PEAK WATER HEATING SYSTEM Filed Nov. 12, 1940 3 Sheets-Sheet 2 JINVENTOR C2 ARK M 05m/wap Bf f/MMA ATTORNEY ited thereto the only'requirement to be met by the structure and mounting of the main thermalswitch 25 being that it will cause opening of the heater circuitcontrolled thereby when substan- I 3l being subjected to hot water inthe upper part of the tank.

While I have illustrated specic details of the main and of the auxiliarythermal switches, I donot desire to be limited thereto and I wish tocall attention also to the fact that while I have shown the auxiliarythermal switch as being positioned at substantially the mid-height ofthe tank, I do not desire to be limited to this particular position. Imay mount it higher up in or on the tank or farther downv in or on thetank and the amount of water referred to when a predetermined fractionalpart of the water content of the tank is mentioned is that correspondingto the position of the auxiliary thermal switch 35. l i

I provide a continuously operative timing means d5 here shown asincluding an electric motor l1 electrically connected'to continuouslyenergized supply circuit conductors 60 and 5l. A worm gear 53 ismounted` on the shaft of motor il and is adapted to mesh with or drive acamvdisc 55 which is mounted on a shaft 5l. The design, construction andadjustment of the parts 4l, 53, 55 and 5l ofthe continuously operativetimer are such that the shaft 5l is caused to rotate throughone-complete turn in twentyfour hours so that a cam disc 59 adjustablymounted thereon will be caused to turn through one complete revolutionin a twenty-four hour day. While I have not shown any bearings for theshaft 5l, these are to be understood as being a part of thethermaltiming means which is electrically connected to the continuouslyenergized supply circuit, in a manner now well known in the art.

The greater part of the periphery of the cam disc 59 is of uniformdiameter while a portion 5I of the periphery is of somewhat larger outerradius for a purpose which will appear. The peripheral extent of theportion 6| of greater outer radius is that which is considered by theengineers of the central power station supplying i I provide a maintimer-controlled heatercontrol switch 53 including a relatively rigidcontact arm 55, a resilient contact arm 6l norumally yieldingly. biasedout of engagement with contact arm t5 but adapted to be moved intoengagement therewith when a lug 55, of electricinsulating material,mounted on the arm 6l is engaged by the portion @i of cam disc 55. It isevident that main timer-controlled switch t3 will be open during all ofthe on-peak period of,

a twenty-four hour day, will be moved into closed position at the startof an oi-peak period and will be held in such closed position during allof an oi-peak period.

I provide also an auxiliary timer-controlled switch li including arelatively rigid contact arm 73 and a resilient contact arm l5 normallyyieldingly biased out of engagement with contact arm 73 but adapted tobe moved into engagement therewith when a lug lll, ofelectric-insulating material, secured to arm l5 is engaged by a camsurface l5 forming part of an adjustable cam member 8l which may besupported by shaft 5l and may be located adjacent to the front surfaceof cam disc 5S, a clamping screw t3 fitting into an arcuate slot 85therein to permit of adjustably setting the member 8i relatively to thecam disc portion 5l.

I vprovide an electromagnetic retardationswitching means 8l here shownas including a coil 09, a magnetizable core 5l having connectedtherewith a contact bridging member 93. A pair of xed contact members 95may be engaged with bridging member 93 under certain operatingconditions of the system which will hereinafter appear.

Supply circuit conductor 59 is connected by a conductor @l and aconductor 99 with contact Aarm 6l while contact arm 65 is connected bycurrent to this system as their oil-peak period y and I have shown thisperipheral extent as being such as to cover approximately an eight-hourperiod. For illustrative purposes we may consider that the oi-peakperiodbegins at 10:00 p. m. and ends at 6:00 a. m. I wish to point out,howeverl that I do not desire to be limited to this particular length ofoff-peak period nor to the starting and the ending time hereinbeforementioned since other cam discs may be substituted, having diierentlengths of nii-peak period portions El and the cam disc 59 may beadjustably mounted on shaft 5l so that not only the time of starting ofvan oit-peak period but also its duration may be adjusted inl accordancewith the desires or demands of the electric distribution systemsupplying current to my vimproved waterheating system.

a conductor mi with one of the iixed contact members and by a conductori033 with one terminal lof coil 89. The other terminal of coil 09 isconnected by a conductor H05 with contact arm '13, while contact arm 'l5is connected by'a conductor 'H01 with contact arm d3 of thermal switch35. A conductor |09 connects contact arm Qi with contact arm 33 and alsowith one terminal of the heater 2l. The other terminal of heater 2l isconnected' by a conductor lll with the other fixed contact member 55.

The operation of the system as to the parts thus far described is asfollows: Let it be-a'ssumed that less than a predetermined fractionallpart of the water content of the tank is hot .tions shown in Fig. 1 ofthe drawings, so vthat the upper auxiliary thermal switch 35 is subjectto cold water in the tank. Under these conditions contact arm 43 willbeout of engagement with contact arm QI and when the maintimercontrolledswitch B3 is moved into the position shown in Fig. 1 of the drawings, anenergizing circuit through the heater 2l will be established as follows:From supply circuit conductor 49 through conductors Sl and l99, throughengaged v contact arms 6l and G5, through conductor IGI, through theengaged contact members 95 and 53 (which'wll be in engagement with eachother because coil 89 is. not energized) through conductor ill, throughheater 2|, through conductor 409, through engaged contact arms 33 and 3|and from there through a conductor H3 to the i 'Ihis will, therefore,cause energization of the heater 2| which energization will beinterrupted bythe action of the main thermal heater control switch 25should substantially all of the water in the tank be' heated before theend of an off-peak period.

Let it be assumed, however, that at the start of an off-peak period suchan amount of hot water in the tank was present as would subject theupper thermal switch 35 to hot water, then contact arms 4I and 43wouldbe in engagement with each other and an energizing circuit for thecoil 89 would be established upon closing of the main timer-controlledswitch and the auxiliary timercontrolled switch 1I at the start of anolf-peak period. It is to be .noted that the position of cam member 8|is such as will cause auxiliary switch 1I to be closed at the start ofan ofi-peak period. The energizing circuit through coil 89 is asfollows: From supply circuit conductor d through conductors @l and 33,through engaged contact arms G1 and E5, through conductors lill and |63,

, through coil S9, through conductor it, through engaged contact arms'E3 and 15, through condoctor lill, through engaged contact arms and di,through conductor |39, through engaged con-1 tact arms 33 and 3| andfrom there through conductor ||3 to the other supply circuit conductorbl.- This will cause energization of the coil 85 and of the core 9| withresultant upward movement of the core member and oi the contact'bridging member 93 into the positions shown in Fig. 1 oi the drawings sothat the herehibeiore described heater-energizing circuit will not beestablished at the start ci an oimpeaii pe d.

if no withdrawal ci hot water occurs during 'the adjustably preset delayperiod, which may he on the order of two or three hours, energizingcircuit of coil 33 will continue, to only at the end of the delay perithe turning movement oi cam su engagement with lug li and gagement or"contact 'l5 fr When this occurs contact brit" t will move intoengagement uned contacts and energization o the heater 2| will occur, tobe engagement with fixed contact members |23 whereas the oppositestatements applied to the energization-delay switch 81. One of the iixedcontact members |23 is connected to conductors 91 and 39, while theother fixed contact |23 is connected by conductor |25 to conductor Thatxed contact |23 having conductor |25 connected thereto has alsoconnected thereto one terminal of coil I I1, while the other terminal ofcoil I1 is connected by a conductor |21 to a resilient contact bar |33of a second auxiliary timer-controlled switch I3|. This switch includesa'resilient contact arm |33 normally yieldingly biased out of engagementwith a relatively rigid contact arm |29 but adapted to be moved intoengagement therewith when a lug |35, of electric-insulating material, onarm |33 is engaged by a cam surface |31 on a second cam member |39 whichis of substantially the same general shape as cam member di. member |39is adapted he adjustably positioned relatively to cam disc v by a clampscrew iti holding member |35 in adinterrupted by the main thermal switch25 if all or substantially all of the wat-er in the tant: be-

comes hot before the end of an o-peak period. Let it be assumed,however, that withdrawal of hot water from the tank occurred during thedelay period with attendant disengagement of contact arm I3 from contactarm 4| because the auxiliary switch 35 is then subjected to cold water,the energizing circuit through coil 83 is interrupted by disengagementof Contact arm I3 from contact arm 4I and the hereinbetore describedheaterenergizing circuit will be closed.

Let it now be assumedthat it is desired to prolong the energization ofthe heater 2| beyond the end of an off-peak period in case all of thewater in the tank is not hot at the end of an olf-peak period and theengineers or the utility supplying current to the user of my waterheating system wish to assure that the daylight part of a twentyfourhour day is started with all or substantially all of the water in thetank hot. In order to do this -I provide the following additional parts.An energization-prolongation electromagnetic switch I I5 which includesa coil I l1, a magnetizable core H9, and a contact bridging member 2|,which latter is adapted to engage with and be disengaged from nxedcontact members |23. It is to be noted that when coil I I1 is notenergized by a current passing therethrough, contact bridging member |2|will be in its lowered position out of justed position adjacent to theiront face of cam disc i desire, however, to point out that while I haveshown vparticular constructions and locations for the com members Si and|39, my invention is not limit-eci to these particular details, whichhave been shown generally only in their simplest form.

,E ig. 2 of the drawings shows the positions ci the parts of the cammembers Si oi the cam disc just before the end oi an oi-peah period. itwill be noted that heater contro?. switch G3 is still in its closedposition since lug 5@ is .still engaged by cani surface Gi earn sur-zface has been moved into engagement with lug on contact to cause moveinto engagement wit-i contact arno |29 or" the sec ond auxiliary switchi controlled. by the timer. lThe closure o1? the second time-controlledswitch |3i effected energiaation coil lil through a circuitsubstantially as follows: From supply circuit conductor d@ throughconductors @l and through engaged Contact arms di and 65, throughconductor lili, through engaged contact arms 93 and 95,'throughconductors iii and |25, through coil il?, through conductor lit',through engaged Contact arms |33 and |29, through a conductor |493 toconductor |09, through engaged contact arms 33 and 3| and from therethrough conductor |63 to the other ductor 5 supply circuit conductor 5l.

The energized coil I i1 therefore causes upward movement of core member||9 and Contact bridg ing member |2|, the latter engaging xed contactmembers |23 to close another energizing circuit through heater 2|substantially as follows: From supply circuit conductor I8 throughconductor 91, through engaged contacts |23 and I2 I, through conductors|25 and IH, the heater 2|, through conductor |39, through engaged con'-tact arms 33 and 3| and from there through conductor ||3 to the othersupply circuit con- This will, therefore, eiect energize.- tion of theheater through another heaterenergizing circuit including'theelectromagnetic prolongation switching means ||5 and the main thermalswitch 25.

As it is desired that energization of the heater 2| be prolonged beyondthe end of the off-peak period, it is necessary to have a holdingcircuit for the coil I I1 which is independent of the main gaged contactmembers i2@ and H2L through coil .l li, through conductor E21, throughengaged contact arms |33 and |23, through conductors |43 and |53,through engaged contact arms 33 and 3| and from there through conductorH3 to the other lsupply circuit conductor 5|. It is, therefore, obviousthat deenergization of the heater 2| can be eiected in two ways, by twodifferent switches depending upon whether all of the water in the tankis hot before the end of the prolongation period or whether less thanall of the water in the tank is hot before the end of the prolongationperiod,'which latter is determined by the peripheral extent of the camsurface |31 as well as by its position relatively to the end of the camsurface Si.

If all of the water in the tank is hot before cam surface |3'i hasbeenturned out of engagement with lug |35 on vcontact arm E33, the thermalheater control switch 25 is effective to interrupt the circuit and oncethis circuithas been interrupted, it will not be reclosed in casewithdrawals of hot watervoccur from the tank before the end of theprolongation period. If, on the other hand, substantially no hot wateris withdrawn from the tank but all of the water in the tank is not hotbefore the end of the prolongation period, energization of the heater 2|will be terminated by reason of the disengagement of contact arm |33from contact arm |29 with attendant deenergization of coil li'l anddisengagement of contact bridging member 2| from xed contact members|23. In this case also withdrawal of hot water occurring before the endof the prolongation period, suflicient to subject main thermal switch 25to cold water, reenergization of the heater will not be eiected sincethe conditions necessary for reenergizing the system, and particularlythe heater 2|, are not present as is apparent from a consideration ofthe energizing circuits and the control-circuits therefor as above setforth.

Referring now to Fig. 3 of the drawings, I have there illustrated aslightly modified form of system which is eective to energize the heater2| at the start of an off-peak period in case less than a predeterminedfractional part of the water content of the tank is hot 'at the start ofan off-peak period, which will delay energization of the heater for anadjustably preset length of time after the start of an off-peak periodin case more than said predetermined fractional part of the water ishot, which will deenergize the heater as soon as al1 or substantiallyall ofthe water in the tank is hot and which will cause prolongation ofthe energization of the heater afterV the end of an olf-peak period ifless than said predetermined fractional part of the water content in thetank is hot at the end of an o-peak period.

In this modification I provide the same or substantially the samecontinuously operative timer parts, a main heater control switch and aiirst and a second auxiliary timer-controlled switch as hereinbeforedescribed. I provide also an energization-delay-electromagnetic switchand an energization-prolongation-electromagnetic switch as washereinbefore described for the system shown in Fig. 1 of the drawings. Iprovide also a main thermal heater` control switch but I provide aslightly modified form of auxiliary thermal control switch |45. Thisswitch includes a tubular member |41 similar to tubular members 21 and31, an expansionrod |49 in the tubular member adapted to engage aresilient contact arm |5| whichis normally yieldingly biased intoengagement with a relatively rigid contact arm |53 terminal of heater2l.

accoglie when the tubular member |61 is subjected to cold water butwhich is adapted to'be moved into engagement with another outerrelatively rigid contact member by rodll when it and the tubular memberUil are subjected to hot water. Contact arm |53 of the auxiliary thermalswitch M5 is connected by a conductor ll to contact arm |39 of thesecond auxiliary time control switch l3l. Contact arm .145i of theauxiliary thermal switch i435 is connected by a conductor |59 to contactarm 3| and to one Contact arm H55 is connected by a conductor itl tocontact arm l5 of the first auxiliary timer-controlled switch 'i l.

Let it be assumed that at the start of an opeak period when the mainheater control switch c3 has just been moved into closed position by thecam surface 6|, as shown in Fig. 3 of the drawings, that the tubularmember lll is subjected to hot water with resultant engagement ofcontact arms |5l and |55, as shown in Fig. 3 of the drawings. In thiscase an energizing circuit through coil 89 of the delay switch di isclosed substantially as follows: From supply circuit conductor tuthrough conductors Si and 99, through engaged contact arms fil and te,through conductor lul to coil 89, through conductor l5 to the engagedcontact arms las and lo, through conductor ll to and through engagedContact arms |55 and I5I, through conductor |59, through engaged contactarms 3| and 33 and from there through the conductor H3 to the othersupply circuit conductor 5|. This will result in magnetizing core memberSi with attendant upward movement thereof into the position shown inFig. 3 of the drawings so that contact bridging member S3 controlledthereby is out oi' engagement with fixed contacts 95so that noenergizetion of the heater 2| will occur.

Let it be assumed, on the other hand, that tubular member |41 andexpansion rod |49 are subject-to cold water in the tank, that is, thattact bridging member 93 is in its lower position where it engagescontacts 95, so that an .energizing circuit through the heater 2i isestablished as follows: From supply circuit conductor 49 throughconductors Sl and S9, through engaged contact arms Sl and 55, throughconductor |0| to and through engaged contacts 35 and 93, throughconductor lll, heater 2l, a part of conductor |59, through engagedcont-act arms 3| and 33 and from there through conductor H3 to the othersupply circuit conductor 5|.

It may be here pointed out that this energization of the coil 2| willcontinue for as long as the circuit through heater 2l ls not interruptedby reason of all of the water in the tank being hot, which interruptionwill be eiected by disengagement of contact arms 3| and 33 of-the mainthermal heater control switch 25, if all or substantially all of theWater in the tank is heated before the end of an oil-peak period.

If it be assumed, for illustrative purposes, that more than saidpredetermined fractional part of the water content of the tank was hot,at the start of an off-peak period, with attendant closure of theenergizing circuit through coil 89 by reason of engagement of contactarms |5| and |55 with each other and of the engagement of contactarms-13 and 15 with each other, and assuming further that no withdrawalsof hot water occur during the delay period (which `would have resultedin disengagement of contact arms and |55 with deenergization of the coil69 and engagement of contact bridging member with contacts 95) it isobvious that contact arm will move out of engagement with contact arm 13at the end of the adjustably preset delay period, which may be assumedto be on the order of two or three hours. At the end of this delayperiod with attendant disengagement of contact arms 15 from contact arm13, coil 39 will be deenergized, assuming that it was energized, asabove stated, and the heater 2| will be energized.

Let it now be assumed that less than a predetermined fractional part ofthe water in the tank is 'hot at the endof an off-peak period, then theenergization-,prolongation switch ||5 and, the auxiliary thermal switchand the second auxiliary time-control switch |3| will effectprolongation of the energization of the heater 2|. The energlzation ofcoil ||1 will be effected through a circuit substantially as follows:From supply circuit conductor 49 through conductors 91 and 99, throughthe engaged contact arms 61 and 65, through conductor |3| to and throughthe engaged contact members 95 and 93, through conductors and |25 to andthrough coil ||1,

through conductor |21 to and through engaged contact arms |33 and |29,through conductor |51 to and through engaged contact arms |53 and |5|,through conductor |59 to and through engaged contact arms 3| and 33 andfrom there through conductor ||3 to the other supply circuit conductor5|. Engagement of contact arms |5| and |53 of the auxiliary thermalswitch |45 is, of course, evident since tubular member |41 is subjectedto the temperature of relatively cold water, as hereinbefore noted.'This 'energizing circuit of coil ||1 causes upward movementof contactbridging member |2| into engagement with contacts |23 whereby anenergizing circuit through heater 2| is closed as follows: From supplycircuit conductor 49 through conductors 91 and 99 to and through engagedcontacts |23- and |2|, through conductors |25 and to and through ltheheater 2|, through conductor |59 to .and through engaged contact members3| and 33 and from there through conductor ||3 to the other supplycircuit conductor 5|.

The above-described coil-energizing circuit of y theenergization-prolongation switch included the main timer-controlledswitch 53 which, of course, will be moved into open position at the endof an off-peak period. A holding circuit for coil ||1 independent of theswitch 93 is provided by my system, substantially as follows: Fromconductor 49 through conductors 91 and 99 to and through engaged contactmembers |23 and |2| through coil ||1, through conductor |21 to andthrough the engaged contact arms |33 and |29, through conductor |51 toand through engaged contact arms |53 and |5|, through conductor |59 toand through the engaged contact arms. 3| and 33 and from there throughconductor |I3 to the other supply circuit conductor 5|. holding circuitfor coil ||1 is independent of the main timer-actuated heater controlswitch 33 and is dependent upon the second auxiliary time control switch|3|, the auxiliary thermal switch 45 and the main thermal heater'control switch 25.

' y It is, therefore, obvious thatshould more than said predeterminedfractional part of the water content of the tank become hot during thepro- ThisV longation period, and before the end of said period, contactarm |5| being moved out of engagement with contact arm |53 will effectdeenergization of coil ||1 and therefore interruption of the energizingcircuit of heater 2| at the prolongation switch contacts |2| and |23..

lIn case less than a said predetermined fractional part of the watercontent of the tank becomes hot before the end of the oir-peak period,disengagement of contact arm |33 from contact arm |29, occurring at theend of the prolongation period, will also deenergize the above describedholding lcircuit and therefore will also deenergize the heater 2|.

Referring now to Fig. 4 of the drawings, I have there illustrated thesame circuit as shown in Fig. 3 of the drawings but have added thereto alow-rate watt-hour meter |63 and a high-rate watt-hour meter |65properly connected and controlled so that all current flowing throughthe heater 2| during an oil-peak period will be registered in thelow-rate meter |63 while all of the current traversing the heater 2|during onpeak hours will .be registered and recorded in -the high-ratemeter |55. To obtain this result I connect one terminal of the twometers |63 and |65 in parallel to a conductor |61 which is connected tothe first supply circuit conductor 49. The other terminal of meter |63is connected by a conductor |69 to a fixed contact member |1| while theother terminal of meter |65 is connected by a conductor |13 'to a fixedcontact member |15. A pivotally mounted contact arm |11 is adapted to beselectively moved into engagement with contacts |1| and |15 by theaction of a relay coil |19 having a core member |8| movable thereinwhich core member is pivotally connected to arm |11. The xed support ofarm |11 is connected by a conductor |93 to conductor 99. -One terminalof coil |15 is connected by a conductor to conductor |21 while the otherterminal of coil |19 is connected by a conductor |91 to conductor Theparts of the system of `lig. 4 are shown in the position which they willoccupy during the prolongation period when the main heater controlswitch 63 is open, the ilrst auxiliary timer-controlled switch 1| isopen, the second auxiliary timer-controlled switch |3| is closed,

the main thermal heater control switch 25 is member |41 is subject tocold water. Conductor |21 is energized, all as has hereinbefore been setforth, during the prolongation period and coil |19 was energizedsimultaneously with the closure of auxiliary switch |3| by reason of theenergization prolongation cam member |39 having effected closure ofswitch 3|.

During the earlier` part of the operation of the Y system, startingeither with the start of an offpeak Aperiod or after a predetermineddelay period, the coil |19 of the wattmeter controlling member would nothave been energized since conductoi 21 was not energized so that switcharm |11 would be in its lower position, shown by the broken lines inFig. 4, so that current flowing through the heater 2| would flow throughlow-rate wattmeter |93.

Referring now to Fig. 5 of the drawings, I have there illustrated astill further modification of a water heating system embodying myinvention in which delay of the energization of the heater is effectedif less than a predetermined` fractional part of the vwater content ofthe tank is hot at the start of an oil-peak period, say on the order ofone-third oi the tank content, and which will eiect prolongation of theenergization of the heater after the end of an oli-peak period ifanother predetermined fractional part of the water content is not; hotat the end of an oil?- peak period, which, for illustrative purposes,may

ybe two-thirds of the tank content. It is to be understood that I do notdesire to be limited to the specific one-third and two-thirds fractionalparts but may make these any desired-parts of the total. The amount inquestion is determined, as has already been hereinbefore set forth, bythe position of a plurality of auxiliary thermal control switchessubjected to the water at diiierent heights in the tank, and for thispurpose I use two auxiliary thermal switches. I provide the continuouslyoperative timing means 45 as already hereinbefore described, a mainheater control switch 93 actuable by the timer, a rst auxiliarytimer-controlled switch 1|, and a second auxiliary timer-controlledswitch |3|. I provide a main thermal heater control switch 25, anenergization-delay electromagnetic switch 81 -and anenergization-prolongatlon electromagnetic switch ||5, as hereinbeforedescribed. For the purposes of this particular modication oi' myimproved hot water system, I provide a rst auxiliary thermal switch |88shown as including a tubular member |89, an expansion rod |90 thereinadapted to engage a resilient contactarm limited to the speciiicpositions of the iirst and' second auxiliary thermal switch as shown inFig. 5 of the drawings but may place them at any part along the heightoi' the tank.

switch 25, and is also less than sufdcient to open the lower auxiliarythermal switch |95, but is suilicient to surround tubular member |89with hot water and cause engagementof contact arms |9| and |93. Theenergizing circuit of coil 89 will therefore be e'ected substantially asIollows: From supply circuit conducto;` I9 through conductors 91 and 99to and through engaged contact arms 81 and y85, through conductor |0| toand through coil 89, from there through conductor 299 to and throughengaged contact arms 13 and 15, through conductor 201, to and throughengaged contact arms |93 and |9|, through conductor 205, through engagedcontact arms 3| and 33 and from there through conductor ||3 to the othersupply lcircuit conductor 5|. 'I'he energized coil 89 will cause thecore 9| and the contact bridging member 93 to occupy the positions shownin Fig. 5 of the drawings vwhereby energization of the heater 2| throughthe electromagnetic switch 81 is prevented. Of course, if the amount ofcold water in the tank at the start of an off-peak period is such thattubular member |89 of the upper switch |88 Ais surrounded .by

cold water, then contact arms |9| and |98 would i be out of engagementwith each other so that the above described energizing circuit of coll89 would not be eiected whereby a heater-'energizing circuit as followswould be provided: From supply circuit conductor 49 through conductors91 and 99 to and through engaged contact arms 61 and 55, throughconductor |0| to and through engaged contact members 95 and 93, throughconductor |I and heater 2|through a part of conductor 205 to and throughengaged contact arms 3| and 33 and from there through conductor ||3 tothe other supply circuit conductor 5|.

One terminal of heater 2| is connected by a conductor 205 with contactarm 3| of the main thermal switch 25 and also4 by conductor 205 withcontact arm I9| of the iirst or upper thermal switch |88. Contact arm 93of the upper auxiliaryythermal switch |88 is connected by a conductor201` with contact arm 15 of the ilrst auxiliary timer-controlled switch1|. Contact arm 13 of switch 1| is connected by a conductor 209 with oneterminal o1' coil 89 of the energization-delay switch 81. A conductor2li connects conductor 205 with contact arm 203 oi! the second auxiliarythermal switch |95 while a conductor 2|3 connects contact arm 20| withcontact arm |29l of the second auxiliary timer-controlled switch |3|.

Let it be assumed, for illustrative purposes, that-the continuouslyoperative timer 45 is in the position shown in Fig. 5 of the drawingsat, a few minutes after the start of an oH-peak Should it occur thatenough water in the upper tact arms |9| and |93 would be moved intoengagement with each other with resultant energization of the coil 89,provided that suiiicient water in the tank is heated to surround tubularmember |89 during the time that the rst auxiliary timer-controlledswitch 1| is in its closed position, which delay period may beconsidered to be on the order oi.' two or three hours. y

It is evident that after contact arm 15 of the rst timer-controlledswitch 1| has been moved out oi engagement with arm 13, the temperaturecondition'aifecting switch |88 no longer has any eilect upon theenergization of heater 2| and such energization will be *interruptedonly in case all of the water in the tank is hot. Disengagement ofcontact arm 83 from contact arm 3| by the action of the main thermalheater control switch will efiect deenergization of the heater.

Let it be assumed, however, that less than enough water in the tank washeated to envelope tubular member |91 before the end oi the offpeakperiod, that is, contact arm 20| is still in engagement with contact arm203 Just before the end of an oil-peak period when main timer controlswitch 83 is still closed and the second auxiliary timer-controlledswitch |3| has been moved into closed. position, it being understoodperiod when main heater control switch 83 is closed, the auxiliarytimer-controlled switch 1| is closed, when the amount of hot water inthe tank is less than sumcient to open main thermal that this secondauxiliary timer-controlled switch |3| is moved into closed position ashort time before the end of an oil-peak period.

Under the above. mentioned conditions an energizing circuit will beclosed throughcoil ||1 substantially as follows: Froml supply circuitconductor 49 through conductors 91 and 99 .to and through engagedcontact arms 61 and 65, through conductor to and through the engagedcontacts 93 and 95, through conductors and |25 topand through coi1 ||1,through conductor |21 to and through engaged contact arms' |33 and |29,through conductor 2|3 to and through engaged contact arms and 203,through conductor 2|| to and through engaged contact members 3| and 33and from there through conductor ||3 to the other supply circuitconductor 5|.

This will energize coil ||1 and provide a prolongation energizationcircuit through heater 2| substantially as follows: From supply circuitconductor 49 through conductors 91 and 99 to and through engaged contactmembers |23 and |2|, through conductors |25 and to the heater 2|,through conductor 205 to and through engaged contact arms 3| and 33 andfrom there through conductor ||3vto the other supply circuit conductor5|.

A-holding circuit for coil ||1 was also established substantially asfollows: From supply circuit conductor 49 through conductors -91 and 99,to and through engaged contact members |23 and |2|, through coil ||1,through conductor,

|21 to and through `engaged contact arms |33 and |29, through conductor2|3 to and through engaged contact arms 20| and 203, through conductor2| to and through engaged contact arms 3| and 33 and from there throughconductor ||3 to the other supply circuit conductor 5|. It will be notedthat this holding circuit for coil ||1 is independent of theI maintimer-controlled switch 53 so that this switch may openv at the end ofan oil-peak period without effecting the continuance of the energizationof the heater 2|. Energization of the heater 2| will be interruptedselectively by the action of the second thermally actuable switch |95when it becomes subject to hot water by reason of the continued heatingof the water in the tank or by reason of the opening of the secondauxiliary timer-` controlled switch |3| at the end of the adjustablypreselected prolongation period.

Referring to Figs. 5 and 6 of the drawings, I have there illustrated amodied form of assembly of the means for effecting closing of the firstand the second auxiliary timer-controlled switches 1| and |3| as by acam surface 2|5 having peripheral extent of say two or three hours andconstituting part of a cam disc 2I1 mounted on shaft 51. The secondauxiliary timer control switch |3| is controlled by an adjustablymounted cam disc 2|9 having a cam surface 22| of larger outer radiuswhich, when it engages lug |35 of contact arm |33, will move this arminto engagement with arm |29. A clamping set screw 223 .permits ofadjustingthe positionl of cam disc 2|3 relatively to cam disc 2| 1 andalso relatively to cam disc 59. The iixed peripheral extent of portion22| of cam 2|9 determines the prolongation period. If it be desired tovary the duration of this period, this may be done by the use of anadditional adjustable cam 225, having an outer radius equal to that ofcam surface 22|, which additional cam may be held by set screw 223, allas shown in Figs. 5, 6 and '1.

Referring now to Fig. '1 of the drawings, I have there shown theconnections which I may employ when providing low-rate wattmeter |33 anda high-rate 'wattmeter |35 connected in the circuit in a manner to cause,current traversing the heater 2| during an olf-peak period to beregistered by the low-rate meter |63 and any current traversing theheater 2| during the onpeak period to iiow through meter |65 to beregistered thereby. All parts and connections which are the same in thisgure as they are in Fig. 5 of the drawings have been given the samenumerals for the sake of simplicity.

The same comments as to the operation of the electromagnetic relay coil|19 in its action upon switch arm |11 as were made hereinbefore whendescribing Fig. 4 of the drawings will apply here also and it is evidentthat I therefore provide relatively simple means, electromagneticallycontrolled, for ensuring that the meters provided for the off-peak andthe onpeak periods will be properly effective to record the current usedby my improved water heating system during the o-peak and the on-peakperiods respectively. l

I have hereinbefore described, in connection with each gure of thedrawings, the operation of the system disclosed in the respectivefigures of the drawings and believe it unnecessary to further amplifysuch descriptions.

The water heating systems employing my inrent. I

While I have illustrated and described certain forms of systemsembodying my invention, it is obvious that further modifications may bemade without departing from the spirit and scope thereof and all suchmodifications clearly coming within the scope of the appended claims areto be considered as being covered thereby.

I claim as my invention:

1. An off-peak waterheating system for a hot water tank having anelectric heater, comprising a continuously operative timer, a pluralityof heater control switches actuable respectively by the timer and bytank water temperature, said timer-controlled switch being adapted to bemoved into closed heater-energizing position at the start of an off-peakperiod and to be held in closed position during such period only and thetemperature-controlled switch being adapted to be held inheater-energizing position until substantially all of thewater in thetank is hot, a heater-encrgization-delay switch jointly controlled by'the timer and tank water temperature and effective to precludeenergization of theheater at the start of an off-peak period in case thetank contains more than a predetermined quantity of hot water at thestart of an od-peak period and a heater-energization-prolongation switchcontrolled jointly by the timer and by the temperature of apredetermined part of the water in the tank and effective to causeprolongation of the energization of the heater beyond the end of anoil-peak period for a fixed length of time in case the tank containsless than a predetermined quantity of hot water at the end of anoil-peak period.

2. An off-peak water heating system for a hot l 5 como: switchelectrically connected m series ject to tank water temperature andadapted to be held in heater-energizing position until substantially allof the water in the tank is hot, an

electromagnetic heater energization delay switch electrically connectedin series circuit reergization of the heater for a preset xed length oftime after the start of an olf-peak period in case the tank containsmore than a predetermined quantity o1' hot water at the start of anoff-peak period and means including an electromagnetic heaterenergization prolongation switch electrically connected inparallelcircuit relation with the timer-controlled heater controlv switch,controlled jointly by the timer and bythe temperature of a predeterminedpart of the water in the tank and adapted to be moved Aintoheater-energizing position before the end of an off-peak period toeffect prolongation of the energization of the heater for a preset fixedlength of time beyond the end of an off-peak period in case the tankcontains lessthan a predetermined quantity of hot water at the end l ofan off-peak period.

3. An oir-peak water heating system for a hot water tank having anelectric heater, comprising a continuously operative timer, a heatercontrol switch movable by the timer into heaterenergizing position atthe start of an olf-peak period and held in such position duringanoipeak period only, a thermally-actuable heater control switchelectrically connected in series circuit with said timer-controlledswitch, subject to tank water temperature and adapted to be held inheater-energizing position until substantialiy all of the water in thetank is hot, an electromagnetic heater-energization-delay switchelectrically connected in series'circuit relation .with thetimer-controlled heater switch and the themaily-actuable heater controlswitch and controlled jointly by the timer and by the temperature of apredetermined part of the water in the tank and selectively eiective tocause energization ofthe heater at the start oi"y an ofipeak period incase the tank contains less than a predetermined quantity of hot waterat the start of an o`peak period, to delay energization of the heaterafter the start of an off-peak period for an adjustably preset length oftime xed by the timer in case the tank contains more than apredetermined quantity of het water -at the start of an off-peak period,to cause deenergization of the heater during the rest of an olf-peakperiod when substantially all of the water in the tank is hot and tocause reenergization of the heater during the rest of an off-peak periodin case withdrawaly of an appreciable quantity of hot water from thetank occurs during that time and means including an electromagneticheaterenergization-prolongation switch electrically con- 2,266,248Acircuit with said timer-controlled switch, subcontains less than avpredetermined quantity of hot water at the end of an off-peak period.

4. An oir-peak water heating system for a hot water `tank having anelectric heater, comprising a continuously operative timer, a heatercontrol switch movable by the timer into heaterenergizing position atthe start of an olf-peak period and held in such position during anoffpeak period only, a thermally-actuable heater control switchelectrically connected in series circuit relation with saidtimer-controlled switch, subject to tank'water temperature and adaptedto be held in heater-energizing position until substantially all of thewater in the tank is hot, an electromagnetic heater-energization-delayswitch electrically connected in series circuit relation with thetimer-controlled switch and the thermally-actuable switch and controlledjointly by the timer and by the temperature of the water at apredetermined point in the tank and eiective to prevent energization ofthe heater for an adjustably preset ixed length of time determined bythe timer, after' the start of an oir-peak period in case morev than apredetermined fractional part of the water content of vthe tank is hotat the start of an oi-peak period and means including an electromagneticadapted to prolong the 'energization of the heater beyond the end of anoit-peak period switch electrically connected in shunt circuit relationwith the timer-controlled switch, controlled jointly by the timer and bythe temperature of the water4 at a certain point in the tank and adaptedto be moved into timer, a plurality of thermally-actuable switchesindividually responsive to tank water temperature at diierent heights inthe tank, an electromagnetic heater-energization delay switch, anelectromagnetic heater energization prolongation switch and electricconnections between all of said switches and said heater to causeclosure 'of the main timer-controlled switch at the start of an oi-peakperiod to effect energization o1' the heater through the maintimer-controlled'` switch, the electromagnetic-energization-delay switchand one of said thermally-actuable switches in case more than apredetermined fractional part of` the water content of the tank is cold,to delay energization of the heater for a preset xed time after start ofan oil-peak period in case less than said predetermined fractional partof the water content is cold, to cause Y prolongation of theenergization of the heaternected in parallel-circuit relation with thetimercontrolled heater-control switch, controlled jointly by the timerand by the temperature of a predetermined part of the water in the tankand adapted .to be moved into heater-energizing position before the endof annif-peak period to v eiect prolongation of thev energization of thebeyond theend of an oil-peak period for a preset fixed length of timethrough the electromagvneticenergization-prolongation switch and saidone thermally-actuable switch in case the tank contains a predeterminedquantity of cold water at the end of an `off-peak period, and to causedeenergization of the heater by said one thermally-actuable switch incase all of the water in the tank is hot.

6. A system as set forth in' claim 1 and including a high-rate meter, alow-rate meter and electrom'agneticmeans for causing said low-rate meterto be connected in current recording circuit with the electric heaterduring an ofi-peak periodvand for causing said high-rate meter to beconnected in current recording circuit with the electric heater duringan energization-prolongation period.

7. A system as set forth in claim 5 and including a high-rate meter, alow-rate meter and electromagnetic means for causing said vlo v-retemeter to'be connected in current recording circuit with the electricheater during 'an nii-peak period and for causing said high-rate meterto be connected in current recording circuit with theV electric heaterduring an energization prolongation period.

, CLARK M. OSTERHELD.

